The Dynamics of Seasonal Distribution of Great Lakes Herring Gulls

Abstract

The dynamics of seasonal distribution in herring gulls [Larus argentatus] from the Great Lakes [USA, Canada] are presented, and various age-dependent aspects are emphasized. Over 12,500 band recoveries were analyzed with the aid of a Fortran computer program (GULL). Additional information on winter distribution was taken from Christmas Bird Counts. Postbreeding dispersal from the breeding colonies occurs during the fall period, Aug.-Nov. Age-dependent movement is characteristic of the winter months. With increasing age, herring gulls display increasing sedentariness, culminating with adults remaining winter residents on the Great Lakes. In addition to specifying the dynamics of herring gull dispersal and distribution, these results contribute to a better understanding of the importance of this potentially hazardous species relative to bird-aircraft collision problems, the phenomenon of partial migration and, indirectly, the age-dependent orientation needs of this species.